At an early stage in the reforms which led from the Breviarium Romanum to the Liturgia Horarum, the (very competent and distinguished) scholar presiding over Hymnology, Dom Anselmo Lentini, proposed to assign a Proper hymn, Omnis expertem, to this feast. Taken from the pre-Conciliar Propers, its ultimate origin was a local Office of our Lady of Lourdes granted to the Diocese of Tarbes (now 'Tarbes et Lourdes') in 1891 by Pope Leo XIII (extended to the Universal Roman Rite by Pope S Pius X in 1907). Its interest is increased by the fact that there are grounds for strongly suspecting that this hymn was composed by the Pontiff himself, Leo XIII, who was (like Pope S Leo the Great) a Latinist of considerable distinction, as well as being an enthusiastic promoter of the cultus of our Lady of Lourdes. Its text is at the bottom of this page.
Other hymns to our Lady which you might like to compare are these**; do you think a stylistic study supports, or otherwise, the attribution of Omnis expertem to Pope Leo?
*Te dicimus praeconio: Also perhaps by Leo XIII, and also composed for the Office of our Lady of Lourdes. Lentini transferred it in the Liturgia Horarum to the Immaculate Conception. Sadly, he changed the stately second line (Intacta Mater Numinis) to the somewhat prosaic Mater Dei purissima, on the grounds that Numinis "sapit mythologiam". (Vide Sacrosanctum Concilium 93; I can see this point when it applies to Olympus or Iuppiter tonans, but is there much wrong with numen?)
*O lux beata and *Sacra iam splendent for the Feast of the Holy Family: certainly by Leo; Lentini knocked a couple of stanzas off the beginning of Sacra, thus turning it into Dulce fit. These two hymns survive from the Breviary into the Liturgia Horarum.
Here is the text of the hymn to our Lady of Lourdes, for those of you who lack a pre-Conciliar Breviary. It is, surely, particularly appropriate at this time this year, as Septuagesima bids us think about the Fall, the Felix Culpa.
Omnis expertem maculae Mariam
edocet summus fidei magister;
Virginis gaudens celebrat fidelis
Ipsa se praebens humili puellae
Virgo spectandam, recreat paventem,
seque conceptam sine labe sancto
O specus felix, decorata divae
matris aspectu! veneranda rupes,
unde vitales scatuere pleno
*Huc catervatim pia turba nostris,
huc ab externis peregrina terris
affuit supplex et opem potentis
*Excipit mater lacrimas precantum,
donat optatam miseris salutem;
compos hinc voti patrias ad oras
Supplicum, Virgo, miserata casus,
semper o nostros refove labores,
impetrans maestis bona sempiternae
Sit decus Patri, genitaeque Proli,
et tibi, compar utriusque virtus,
Spiritus semper, Deus unus, omni
* Lentini proposed to omit these two stanzas. Huc, hinc seemed to him to imply a Gallocentric world view!